This invention relates to a multi-function copying machine capable of editing picture data. In a copying machine in which an original is read by raster scanning and is copied by a recording head such as a thermal head, multi-color recording or recording both sides of an original (herein two-side recording) is carried out by using a plurality of recording heads.
FIG. 1 illustrates schematically the principle of a copying machine which performs two-color recording utilizing the technique of thermal transfer. In this copying machine, first and second thermal heads 2 and 3 are spaced by a predetermined distance from each other on one side of a recording sheet 1 conveying path. For instance, a black recording ink donor sheet 4 is supplied to the first thermal head 2, while a red recording ink donor sheet 5 is supplied to the second thermal head 2. Pressure rollers 6 and 7 are provided on the opposite side of the recording sheet conveying path to push the recording sheet 1 against the thermal heads 2 and 3.
In this copying machine, the recording sheet 1 is moved in the direction of the arrow (right to left), so that black recording is carried out by the first thermal head 2 and red recording is performed by the second thermal head 3. The thermal heads 2 and 3 are somewhat shifted in the direction of movement of the recording sheet 1 (in the auxiliary scanning direction). Although the thermal heads are shifted as described above, coincidence of the recording positions is essential. For this purpose, a memory 8 is employed in which red picture data are temporarily stored.
FIG. 2 illustrates schematically the principle of a copying machine which performs two-side recording. In this copying machine, a first thermal head 2 is disposed on one side of the recording sheet 1 conveying path and a second thermal head 3 is disposed on the other side of the conveying path. The same recording color ink donor sheets 9A and 9B are generally supplied to the two thermal heads 2 and 3, that is, monotone copying takes place.
In the copying machine of FIG. 2, two-side recording is carried out by moving the recording sheet 1 in the direction of the arrow and driving the two thermal heads 2 and 3. In general, an original is read in such a manner that, after one side is read, the other side is read. Accordingly, it is necessary for a memory 8 to store picture data which are to be recorded by, for instance, the second thermal head 3.
Most of the copying machines which carry out multicolor recording or the like by digital signal processing employ a relatively large capacity memory to store picture data, as described above. However, the memory of this type is used only for its original primary purpose of delaying picture signals. Thus, the efficiency of use thereof is low, which makes the copying machine relatively expensive relative to its scope of utilization.